Description
Glycogen storage disease is an autosomal recessive genetic disease that involves disorders of metabolism. The disease is caused by defects in a gene that code for certain enzymes. Enzymes are responsible for conversion of one substance into another. The enzymes that are absent are those that covert glycogen to glucose, thereby causing an accumulation of glycogen in certain tissues and a lack of glucose needed for energy and muscle activity. The defect is usually present in childhood, though there are some types of this disease that have adult onset.

The following are eight types of Glycogen Storage Disease. Type III or Forbes-Cori Disease affects the Sephardic Jewish Community while Type Ia or von Gierke disease affects the Ashkenazi Jewish Community.

Symptoms
GSD TYPE IA
The most frequent first symptoms noted in infants with GSD Ia include an enlarged liver and low blood sugar (hypoglycemia) due to difficulty controlling the blood sugar. This often results in chronic hunger, fatigue, and irritability. Other symptoms that may develop include: a variety of biochemical abnormalities and delayed growth and development seizures, an enlarged liver, renal problems, slow growth and short stature, can be fatal.

GSD TYPE III
This disorder may cause systemic symptoms but in some cases it is limited to specific tissues. Symptoms include muscle cramping and weakness, although some types of GSD cause more severe symptoms of hypoglycemic seizure and enlarged heart. Other types manifest enlarged spleen and liver as well progression to liver cirrhosis in adults and growth retardation in children.

Incidence and Carriers
Disease frequency: GSD I occurs 1 in 20,000 Ashkenazi Jews and in 1 in 100,000 in general population. The Carrier frequency for GSD Ia among the Ashkenazi Jewish population is approximately 1/130 with the carrier frequency for US general population currently unknown.

Disease frequency: GSD III occurs in 1 in 5400 North-African Jews and in 1 in 200,000 in the general population. Carrier frequency: Estimated to be 1 in 35 in North African Jews.

The disease is transmitted through heredity. Both parents have to carry the mutated gene for there to be a possibility of transmission to their child.
If both are carriers:
 There is a One in Four chance that the child will inherit the mutated gene from each parent and have the disease
 There is a One in Four chance that the child will inherit normal genes from both parents and be completely free of the disease.
 There is a Two in Four chance the child will inherit one of a mutated gene from one parent and a normal gene from the other parent, and in this case, be a carrier like the parents, but free of the disease.

Treatment
Treatment for GSD involves providing the body with an outside supply of glucose Although no specific treatment is available for GSD dietary restrictions has proven to be effective in the management of the disorder. Careful and strict adherence to a dietary regimen may reduce liver size, prevent hypoglycemia, reduce muscular symptoms, and allow for growth and development.

GSDnet
An electronic mailing list intended to allow communication between families, individuals, and professionals with an interest in glycogen storage disease.
To subscribe to GSDnet, send this message:
subscribe to this address: listserv@maelstrom.stjohns.edu
Leave the subject line blank.